As electronic commerce enters into a rapid growth period, the size of online advertising market, which is the main source of revenue for most websites, has increased enormously and continues to grow at a very fast pace. In China alone, for example, the online advertisement revenue reached seven billion RMB in 2007. Optimizing strategies for displaying online advertisement may not only increase primary cash flow return for website owners, but also improve advertising effectiveness for advertisers. Along with an explosive increase in the number of websites, particularly medium-sized and small-sized websites, a key factor in the ad placement optimization is how to improve the impression values of the advertisements placed in various positions on various web pages.
Because qualities and contents vary among websites, the time spent by a surfer on browsing different web pages may be very different. If the time spent on a web page by a surfer is too short, an advertisement that is hosted on the web page may not be noticed by the surfer. In comparison, some web pages of better qualities and substantial contents have good web traffics, and therefore can attract a surfer to spend more time browsing the web pages. However, if the surfer sees the same advertisement for this whole period of time, it can still be a loss to both the website owner and the advertiser because of low advertisement effectiveness.
In existing technologies, simple rotational advertising is used to increase profits for website owners. This simple rotational advertising is mechanically oriented at a single web page. Therefore, advertisements seen by a surfer when multiple web pages of a website are opened may belong to the same advertisement group. If the browsing time spent by the surfer is too short, the surfer may only see the first rotated advertisement every time. This may lead to an unbalance in respective frequencies for displaying different advertisements, and easily cause resistance of the surfer. As a result, the rotational advertising has only limited effectiveness.